1. Field of Invention
In mechanical filleting fish two contrary demands have to be met in that fillets entirely free of bones are to be produced on the one hand and no measurable amount of fish meat is allowed to be lost on the other hand. 2. Description of Prior Art
In the German Pat. No. 1,454,082 a filleting machine for fish has a pair of pinbone knives on each side of the path of the fish, the pinbone knives of each pair being arranged in parallel and spaced relation one to another.
In the U.S. Pat. No. 3,570,048 an apparatus for producing fish fillets free of pinbones has two pairs of circular knives set at an angle to each other with their cutting edges almost in contact at the narrowest point.
With a machine or an apparatus of the aforesaid patents fillets of fish may be produced, but occasionally remainders of the pinbones will be found in the fillets making it necessary, to control both cuts in each fillet.
If -- in order to overcome this problem -- the distance between the two pinbone knives of one pair of pinbone knives or the distance of their cutting edges would be enlarged, another problem would arise, in that there is no possibility of severing the skin of the strip containing the pinbones from the skin of the fillet.
It is a primary object of the invention to produce fillets entirely free of remainders of pinbones and to sever the skin of the strip containing the pinbones from the skin of the fillet.
According to the invention a filleting machine for fish producing fillets of fish including the belly flaps entirely free of bones which has a path for conveying a fish in the direction of its main backbone, means for conveying a fish with its tail end ahead and its belly downwards, a pair of belly filleting knives, a pair of back filleting knives and a pair of separating knives and a pair of rib knives, a pair of upper pinbone knives is arranged between the back filleting knives and the separating knives, a pair of lower pinbones knives is arranged between the separating knives and the rib knives, the upper pinbone knives are cutting in a plane situated above the pinbone of a fish and the lower pinbone knives are cutting in another plane spaced from and lying below the cutting plane of the upper pinbone knives, deflectors for the back muscles of a fish are placed in front of and guiding plates are placed behind the separating knives, the guiding plates extend in the plane of the upper pinbone knives up to the lower pinbone knives, hold down means below and in tight relation to the lower pinbone knives are arranged in front of the latter and control means of known structure are provided operating in dependence on the conveyance of a fish actuating first the two upper pinbone knives to move one against the other as the end of the belly of a fish has passed by, thus making a first pair of incisions above the pinbones, and then the two lower pinbone knives to operate in the same manner to make a second pair of incisions below the pinbones along the belly cavity of the fish.
According to an advantageous embodiment of the invention in a fish filleting machine the rib knives are inclined one to the other and spaced apart with the highest portions of their cutting edges and a pair of strip cutting knives is arranged in the planes extending into the space between the rib knives.
The advantages achieved by the invention are particularly to be seen in the fact, that the fillets produced by the filleting machine are absolutely free of pinbones and need no trimming while the strip containing the pinbones may be handled independently from the fillets, for instance for the production of minced fish.